1. Field of the Invention
This invention relates to a process for the preparation of cobalt (III) acetylacetonate wherein cobalt (II) acetylacetonate is reacted with hydrogen peroxide in the presence of acetylacetone to give cobalt (III) acetylacetonate. The reaction is carried out with a dissolved starting product prepared in a special manner.
2. Discussion of the Prior Art
It is known from German Auslegeschrift No. 24 20 691 (NOA 75 03 276) to react cobalt (II) acetylacetonate with hydrogen peroxide and acetylacetone to give cobalt (III) acetylacetonate. There a cobalt (II) acetylacetonate is used which has been prepared by reacting a cobalt (II) salt in an aqueous solution with acetylacetone by known procedures. A cobalt (II) acetylacetonate produced in this manner always contains two moles of water of crystallization, and these can only be eliminated by very costly means.
Moveover, in this prior-art process the oxidation is carried out in any desired organic solvent, the preferred solvents being aromatic hydrocarbons or alcohols. A drawback of this process is that a previously prepared cobalt(II) acetylacetonate must be used whose preparation is itself very costly. The reason for this is that in these known production processes the reaction product must be neutralized with ammonia, following which the ammonium salts must be carefully washed out.
Even though pure cobalt(II) acetylacetonate is used, in the process of German patent application DAS 24 20 691 the yields of anhydrous cobalt(III) acetylacetonate range only from 75 to 85%.
Thus there has been a need for preparing cobalt(III) acetylacetonate in such a way that yields of preferably over 95% are obtained. There has further been a need for developing a process for the preparation of cobalt(III) acetylacetonate which does not require the use of isolated cobalt(II) acetylacetonate as a starting material.